EnViBo: Embedded Network for Vital Sign and Biomedical Signal

MonitoringGustavo Meneses Benavides

University of San BuenaventuraJuan Diego Lemos Duque

University of Antioquia

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Outline

MotivationIntroductionThe EnViBo Approach EnViBo Platform ArchitectureNetwork NodesNode’s ArchitectureNetwork Deployment and Data AcquisitionResultsConclusions and Future Work

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Motivation

A survey performed in Colombia´s local market regarding suppliers of electronic equipment and parts showed that there is no availability for monitoring solutions at the time this articles is written, therefore, currently the Colombian users must import platform hardware and software for monitoring applications, which increase significantly their cost.

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Introduction

Ambulatory monitoring of vital sign and biomedical signals covers a wide spectrum of applications in different contexts nowadays and has been a research topic during the last decade. The plethora of IEEE 802.X communication standards, favors greatly the development of wireless sensor networks ranging from body-area to wide-area coverage.

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EnViBo: Embedded Network for Vital Sign and Biomedical Signal Monitoring

We present a monitoring platform called EnViBo which is based on a three level architecture; this platform integrates sensor nodes that use moderate-cost elements and Microchip’s IEEE 802.15.4-based royaltie-free protocol named MiWi P2P for communications.

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EnViBo Platform Architecture

At the lower layer nodes communicate with MiWi P2P protocol. In the intermediate or Local Data-sink Layer, we have a computer-based user interface. At the upper layer or Global Datasink, we have interfaces developed to run on computers, tablets and smartphones.

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Distinctive Features for Dexternet and EnViBo Platform Architecture

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Network Nodes: PAN CoordinatorThe PAN Coordinator has been implemented on a 16-bit microcontroller, PIC24FJ128GA010. This unit transfer measurement data collected by vital sign and biomedical signal sensor nodes to the computer-based local data-sink. A secure digital (SD) card has been added to provide local data logging capabilities.

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Network Sensor NodesFive sensor nodes have been developed in order to perform monitoring applications using EnViBo platform, these nodes transmit body temperature, pulse, respiratory rate and activity data. Temperature, pulse and activity measurements obtained from the sensor nodes have shown good reliability.

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Node’s Architecture

Nodes for monitoring other vital sign and biomedical signals can be developed adapting the signal conditioning circuitry to the eight-bit generic sensor node board or following the node architecture model and platform reference documentation.

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Flow DiagramsFirmware Flow Diagram for Personal Area Network Coordinator Firmware Flow Diagram to be

executed for EnViBo Sensor Nodes

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Network Deployment

To conduct an experiment or session related to biomedical signal ambulatory monitoring the person needs to attach the sensor nodes over his body parts by using the attaching means provided along with the network units.

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EnViBo Packet Transfer & Networking

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Data Acquisition Interface

A virtual instrument runs on a computer in order to perform tasks regarding data acquisition and also permits visualizing, registering, processing, printing, analyzing and re-transmitting data towards the upper level of EnViBo platform architecture by means of protocols and technologies like UDP, TCP-IP, SMTP and others.

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Results Moderate-cost Approach for Sensor NodesA moderate-cost approach has been adopted for developing the sensor nodes. A royaltie-free protocol, MiWi P2P from Microchip, is used for communications; the IDE for programming the microcontrollers is for free, the same for the C18 and C30 compilers used to program the network units.

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Performance Tests

In order to follow node’s performance, the firmware which runs at PAN coordinator’s side has been modified to report individual and total number of packets after receiving messages from sensor nodes.

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Battery Performance An important concern for all monitoring platforms is energy consumption of sensor nodes, the tests conducted for monitoring applications by using EnViBo platform have shown that rechargeable batteries present the best performance. The assessment was based in features like cost, operation time and battery lifetime.

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Platform Support

Documents supporting the development of new nodes, node identification and network addresses, modifying nodes firmware and managing the virtual instrument interface are available to support EnViBo platform users. Schematic and printed circuit board designs for developing new nodes or adapting them for sensing other variables are also available

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User Interface for Smartphones

The programming tool named AppInventor (Massachusetts Institute of Technology), has been adopted for developing an interface that run under Android operating system in smartphones by getting Coordinator’s data via serial port emulated RFComm. App inventor functionalities like TinyDB and TinyWebDB are to be added to smartphone interface in order to provide datalogging functionalities for the users.

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Conclusions

A platform for ambulatory monitoring of vital sign and biomedical signal has been developed based on concepts of moderate-cost nodes and the use of commonly available elements. Software and firmware resources and technical documentation has been developed in order to support the network deployment and node configuration for indoor-outdoor applications within the range of PANs.

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Conclusions

A virtual instrument has been developed; it allows covering most of the needs of researchers in order to analyze the data collected by sensor nodes on-line or off-line, additionally the special features of Labview for file input-output operations, report generation and communications, among others, serve to extend the capabilities of EnViBo platform.

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Conclusions

A web page that serves as the platform repository is under continuous development to share software, firmware, node’s electronic design templates and technical documentation. This project is intended to become open source. Interfaces which will run on smartphones and tablets to receive network data sent by IEEE 802.15.1 and IEEE 802.11 transceivers are being developed.

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Future Work

In order to comprehensively evaluate system’s performance a set of field experiments must be designed involving persons wearing the sensors and performing activities in different scenarios. Routing nodes are not included in this first version of EnViBo Platform, some preliminary tests have shown that this type of intermediary nodes must be needed in indoor applications with presence of many walls, doors, furniture, electronic appliances and other obstacles.

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References•P. Kuryloski, A. Giani, R. Giannantonio, K. Gilani, R. Gravina, V. Sepp, P. Yan, A. Y. Yang, J. Hyttinen, S. Sastry, S. Wicker, and R. Bajcsy, “DexterNet : An Open Platform for Heterogeneous Body Sensor Networks and Its Applications ∗,” in BSN ’09 Proceedings of the 2009 Sixth International Workshop on Wearable and Implantable Body Sensor Networks, 2009, pp. 92–97.

•Microchip Technology inc., “Microchip MiWi P2P Wireless Protocol,” 2010

•IEEE Computer Society, IEEE Standard for Telecommunications and information Local and metropolitan area networks — Specific requirements Part 15 .4 : Wireless Medium Access Control ( MAC ) and Physical Layer ( PHY ) Specifications for Low-Rate Wireless Personal Area Networks, IEEE Std 802.15.4™-2006(Revision of IEEE Std 802.15.4-2003), September 2006.

•[Online] Available: https://sites.google.com/site/enviboplatform

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